This preview shows page 1. Sign up to view the full content.
Unformatted text preview: = (10 g) (4.2 J/g°C) (100°C) = 4200 J
If you continue to add heat energy once the temperature of the water reaches 100°C ,the boiling temperature, the heat absorbed is called the heat of vaporization (Lv). This heat is used to cause a change of
phase (from a liquid to a vapor). This heat is increasing the potential energy of the molecules of the liquid.
No temperature change takes place. Each substance has its own heat of vaporization. The heat of vaporization for water is 2270 Joules/g. Exactly the same amount of heat is given up when 1.0 g of water vapor is
changed to liquid water. This heat is called the heat of condensation.
The general equation for calculating heat energy to change a liquid to a gas (vapor) is:
Heat = Mass x Heat of Vaporization
Q = m Lv
H2O(s) at -20°C 10 g B-C
H2O(s) at 0 °C 10 g C-D
H2O(l) at 0°C 10 g D-E
H2O(l) at 100°C 10 g E-F
H2O(g) at 100°C 10 g H2O(g) at 140°C 10g CHEMISTRY HEATING CURVE WORKSHEET Calculate the heat necessary to change 10 g of H2O(l) at 100°C to 10 g of H2O(g) at 100°C.(D-E) Q =...
View Full Document
- Winter '14